This application relates generally to the field of roof and attic ventilation systems, and more particularly to devices or systems commonly referred to as rafter vents, baffle vents, attic insulation vents, venting channels or under-roof-deck vents (to be referred to hereinafter collectively as rafter vents and rafter vent systems). In general, rafter vent members and rafter vent systems are utilized to provide ventilating air flow beneath the deck members of roof systems, and are of particular use when under-deck or rafter attic insulation products are utilized to reduce heat transfer from the roof into the attic, such as for example fiber mats or batts secured by mechanical fasteners or foaming insulation sprayed-in-place on the underside of the deck members between the attic rafters, since the presence of this insulation blocks air flow along the underside of the deck members. The positioning of rafter vents between the roof deck members and the insulating material, if present, increases the air flow beneath the roof decking lowers the temperature of the roof, thereby decreasing the damaging effects of high temperature on the roof membrane, shingles, etc.
It is known to provide rafter vent members that are positioned under the deck members and between the rafters prior to installation of the attic insulation, the rafter vent members being structured to form one or more elongated channels or chutes that enable air to flow upwardly along the underside of the roof from the soffit area eave vents to the ridge or roof vents located at or near the ridge board. Examples of such rafter vent systems are shown in U.S. Pat. Nos. 5,596,847, 8,562,400, 4,406,095, and 4,237,672. The rafter vent members are typically formed from thin plastic sheets and may be positioned atop the rafters prior to installation of the roof decking. Alternatively, the rafter vent members may be placed between the rafters after installation of the decking on the rafters, the rafter vent members being secured with mechanical fasteners, adhesive, or a friction-fit structural design. With the rafter vent members in place, the rafter vent members maintain under-deck ventilating channels after the internal attic insulation has been applied to the underside of the rafter vent members. As the temperature of the roof increases because of high ambient temperatures and exposure to sunlight, air occupying the passage between the rafter vent members and the underside of the roof deck members is warmed by heat induction through the roof, causing the warm air to rise and exit through roof vent or ridge vent outlets while simultaneously drawing in cooler air through the eave vents.
These systems have proven to work satisfactorily when used on the portions of the roof where the rafters, typically referred to as common rafters, fully extend from the eaves to the roof ridge, such that heated rising air may pass through roof or ridge vents and cooler air may be drawn in through the eave vents. However, a problem arises in that rafter vent members will not properly function in roofs having jack rafters, defined as rafters that do not extend fully between the eaves and the roof ridge, such as found in hip roofs or valley roofs. In hip roofs the jack rafters extend from the eaves up to the angled hip rafters rather than to the horizontal roof ridge boards, and there are no upper outlet vents for release of heated ventilated air into the atmosphere. Thus, air in the passages between adjacent jack rafters remains trapped. Similarly, in valley roofs the jack rafters extend from the horizontal roof ridge board to the angled valley rafters rather than to the eaves, so there are no lower inlet vents to receive cooler venting air and air in the passages remains trapped.
It is an object of this invention to provide a rafter vent system that is suitable for use with jack rafters as found in hip roofs or valley roofs, whereby a combination of hip rafter bypass channel members form an upwardly extending bypass channel or chute along the underside of the hip rafter that receives heated air from the upper ends of the rafter vent members positioned between the hip jack rafters and delivers it upwardly to the area of the ridge board and ridge vents, or whereby a combination of valley rafter bypass channel members form an upwardly extending bypass channel along the underside of the valley rafters that receives cooler venting air from the eave vents and delivers it into the lower ends of the rafter vent members positioned between the valley jack rafters. It is a further object to create in hip roofs and valley roofs a complete ventilating pathway beneath the deck members of a roof which extends from the eave vents to the ridge vents.